US3963325A - Wide angle lens - Google Patents

Wide angle lens Download PDF

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Publication number
US3963325A
US3963325A US05/570,150 US57015075A US3963325A US 3963325 A US3963325 A US 3963325A US 57015075 A US57015075 A US 57015075A US 3963325 A US3963325 A US 3963325A
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US
United States
Prior art keywords
sub
lens
positive
wide angle
convex
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US05/570,150
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English (en)
Inventor
Yasuo Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pentax Corp
Original Assignee
Asahi Kogaku Kogyo Co Ltd
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Filing date
Publication date
Application filed by Asahi Kogaku Kogyo Co Ltd filed Critical Asahi Kogaku Kogyo Co Ltd
Application granted granted Critical
Publication of US3963325A publication Critical patent/US3963325A/en
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Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
    • G02B9/62—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having six components only
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Definitions

  • the present invention relates to a retrofocus type wide angle lens the length of which is reduced.
  • the retrofocus type lens compact in size one of which is to reduce the diameter of the lens and the other is to reduce the length of the lens system. This invention is concerned with the latter way to make the lens compact.
  • the present invention provides a wide angle lens system comprising six lens components constituted by six lens elements wherein the first lens is a negative meniscus lens convex to the object, the second lens is a positive lens, the third lens is a positive lens, the fourth lens is a biconcave negative lens, the fifth lens is a positive meniscus lens convex to the image and the sixth lens is a positive lens, wherein the following conditions are satisfied;
  • FIG. 1 is a longitudinal view showing the lens in accordance with an embodiment of the present invention.
  • FIGS. 2a to 2d show aberration curves obtained by lens system in accordance with the embodiment shown in FIG. 1.
  • the first lens L 1 is a negative meniscus lens convex to the object (which means that the face of the greater radius of curvature is on the object side), and the second and third lenses L 2 and L 3 are positive lenses.
  • the fourth lens L 4 is a biconcave negative lens
  • the fifth lens L 5 is a positive meniscus lens convex to the image
  • the sixth lens L 6 is a positive lens.
  • the lens system in accordance with the present invention comprises the above six lenses L 1 to L 6 and satisfies the following conditions:
  • F 1 .2....i effective focal length of the lens system comprising the first to the i-th lenses
  • r j radii of curvature of the j-th face
  • d k axial air separations or thicknesses of the k-th air separation or lens thickness
  • n i the refractive indices for the sodium d-line of the i-th lens
  • ⁇ i Abbe numbers of the i-th lens.
  • the first conditions (1) are to be satisfied for obtaining the reduced length of the lens system.
  • the degree of negativeness of the first lens is required to be increased to reduce the length of the lens system.
  • the focal length of the first lens is so short as to be less than F/1.2, the radius of curvature of the second face becomes too small and coma aberration appears. In order to eliminate the increased coma aberration, other aberrations will be increased. If the focal length of the first lens is longer than F/0.8, the purpose of obtaining a compact lens system cannot be achieved easily within the limitation of the third conditions.
  • the second conditions (2) are to be satisfied in connection with the first conditions to determine the positive refractive power of the second and third lenses for correcting chromatic aberration with reference to d 6 or the refractive index of the glass material.
  • F 1 .2,3, is shorter than F/1.8, chromatic aberration is well corrected but the radii of curvature of the respective faces become too short and coma aberration and other aberrations will increase. Further, Petzval sum is reduced and it becomes difficult to design a wide angle lens of high performance.
  • the focal length is longer than F/1.4, the air separation d 6 must be enlarged, which results in reduction of Petzval sum and dissatisfaction of the fourth conditions (4).
  • the third conditions (3) are to be satisfied for making the lens system compact. If the separation d 2 is shorter than 0.2F, the back focal distance must be elongated by some other means in order to make the lens system be of retrofocus type, which results in dissatisfaction of the other conditions or increase in aberrations. If the separation is longer than 0.45F, it becomes difficult to reduce the length of the lens system.
  • the fourth conditions (4) are to be satisfied for obtaining a compact wide angle lens. If the value defined here is smaller than 0.7F, the correction of aberration becomes difficult. It it is larger than 0.9F, the overall length of the lens system becomes to long.
  • the fifth conditions (5) are to be satisfied for keeping the Petzval sum normal to correct for chromatic aberration in connection with Abbe numbers of the first, second and third lenses. If the value defined here becomes smaller than 0.2. the refractive index n 1 increases and Abbe number must be reduced, which results in an imbalance in chromatic abberation. If n 1 is kept as it is, n 2 and n 3 are reduced and Petzval sum increases and the radii of curvature are shortened, which results in a general degradation of aberrations. If it becomes larger than 0.32, n 1 decreases or n 2 and n 3 increase, which results in degradation in correction of aberrations and increase in cost of glass material and reduction of Abbe numbers. The chromatic aberration is accordingly degraded. Further, Petzval sum is decreased as a whole and the correction of aberration in a large angle becomes difficult.
  • the radii r 1 to r 12 and thicknesses and separations d 1 to d 11 , along with the refractive indices n 1 to n 6 and Abbe numbers ⁇ 1 to ⁇ 6 for lenses L 1 to L 6 are given in Table 1 as follows:
  • FIG. 2a shows the spherical aberration and the sine condition
  • FIG. 2b shows the chromatic aberration
  • FIG. 2c shows the distortion
  • FIG. 2d shows the astigmatism of the lens system shown in FIG. 1 and defined in Table 1.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)
US05/570,150 1974-04-24 1975-04-21 Wide angle lens Expired - Lifetime US3963325A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JA49-46104 1974-04-24
JP49046104A JPS5918682B2 (ja) 1974-04-24 1974-04-24 広角レンズ

Publications (1)

Publication Number Publication Date
US3963325A true US3963325A (en) 1976-06-15

Family

ID=12737676

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/570,150 Expired - Lifetime US3963325A (en) 1974-04-24 1975-04-21 Wide angle lens

Country Status (4)

Country Link
US (1) US3963325A (fr)
JP (1) JPS5918682B2 (fr)
DE (1) DE2518087B2 (fr)
GB (1) GB1454715A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4182549A (en) * 1978-09-11 1980-01-08 Vivitar Corporation Compact wide angle lens
US4303315A (en) * 1978-09-11 1981-12-01 Vivitar Corporation Compact wide angle lens
US6353509B1 (en) * 1999-09-09 2002-03-05 Fuji Photo Optical Co., Ltd. Wide-angle lens
CN110007435A (zh) * 2014-01-17 2019-07-12 大立光电股份有限公司 摄影光学镜头及取像装置
CN112485885A (zh) * 2019-09-12 2021-03-12 信泰光学(深圳)有限公司 成像镜头

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5944014A (ja) * 1982-09-06 1984-03-12 Sony Corp 広角レンズ
JPH1123961A (ja) * 1997-07-03 1999-01-29 Fuji Photo Film Co Ltd 広角レンズ
JP6537027B1 (ja) * 2018-08-14 2019-07-03 エーエーシー テクノロジーズ ピーティーイー リミテッド 撮像光学レンズ

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037426A (en) * 1957-09-27 1962-06-05 App De Prec Kinoptik Photographic objectives having a large angular field

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037426A (en) * 1957-09-27 1962-06-05 App De Prec Kinoptik Photographic objectives having a large angular field

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4182549A (en) * 1978-09-11 1980-01-08 Vivitar Corporation Compact wide angle lens
US4303315A (en) * 1978-09-11 1981-12-01 Vivitar Corporation Compact wide angle lens
US6353509B1 (en) * 1999-09-09 2002-03-05 Fuji Photo Optical Co., Ltd. Wide-angle lens
CN110007435A (zh) * 2014-01-17 2019-07-12 大立光电股份有限公司 摄影光学镜头及取像装置
CN110007435B (zh) * 2014-01-17 2021-09-17 大立光电股份有限公司 摄影光学镜头及取像装置
CN112485885A (zh) * 2019-09-12 2021-03-12 信泰光学(深圳)有限公司 成像镜头
CN112485885B (zh) * 2019-09-12 2022-03-29 信泰光学(深圳)有限公司 成像镜头
US11624895B2 (en) 2019-09-12 2023-04-11 Sintai Optical (Shenzhen) Co., Ltd. Lens assembly

Also Published As

Publication number Publication date
JPS50138824A (fr) 1975-11-06
GB1454715A (en) 1976-11-03
DE2518087B2 (de) 1977-05-18
DE2518087A1 (de) 1975-10-30
JPS5918682B2 (ja) 1984-04-28

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